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Fluorescent mannosides serve as acceptor substrates for glycosyltransferase and sugar-1-phosphate transferase activities in Euglena gracilis membranes

Ivanova, Irina M., Nepogodiev, Sergey A., Saalbach, Gerhard, O'Neill, Ellis C., Urbaniak, Michael D., Ferguson, Michael A.J., Gurcha, Sudagar S., Besra, Gurdyal S., Field, Robert A.
Carbohydrate research 2017 v.438 pp. 26-38
Euglena gracilis, algae, enzymes, fluorescence, high performance liquid chromatography, mass spectrometry, polysaccharides
Synthetic hexynyl α-D-mannopyranoside and its α-1,6-linked disaccharide counterpart were fluorescently labelled through CuAAC click chemistry with 3-azido-7-hydroxycoumarin. The resulting triazolyl-coumarin adducts, which were amenable to analysis by TLC, HPLC and mass spectrometry, proved to be acceptor substrates for α-1,6-ManT activities in mycobacterial membranes, as well as α- and β-GalT activities in trypanosomal membranes, benchmarking the potential of the fluorescent acceptor approach against earlier radiochemical assays. Following on to explore the glycobiology of the benign protozoan alga Euglena gracilis, α-1,3- and α-1,2-ManT activities were detected in membrane preparations, along with GlcT, Glc-P-T and GlcNAc-P-T activities. These studies serve to demonstrate the potential of readily accessible fluorescent glycans as substrates for exploring carbohydrate active enzymes.